This project represents a multidisciplinary investigation of the basic structure of the protein and mineral portions of hard tissue. Such techniques as x-ray diffraction, infrared absorption spectrophotometry, radiotracer methods, electron microscopy and electron diffraction are utilized in this study. The term structure, as used here, means the identification of the chemical phase or phases present in hard tissue and the atomic and/or molecular arrangement of the chemical constituents of these phases. These studies will be made on normal and pathological hard tissue as well as on synthetic, chemical systems related to hard tissue. A second objective of this project will be the study of the calcification process. The nucleation of bone and tooth mineral and the nature of pathological mineralization will be the subject of investigation. The nucleation and growth as well as the structure of relevant calcium phosphates will be studied. Finally, the chemistry of the calcification of cartilage will be included in this study.